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Press Release

Contamination in Pools Reduces Chlorine Effectiveness

ATLANTA Contamination of swimming pools by fecal matter from leaky diapers dramatically
reduces the ability of chlorine to kill the waterborne parasite Cryptosporidium,
according to an article in the current issue of Emerging Infectious Diseases, CDC's
peer-reviewed journal, which tracks new and reemerging infectious diseases worldwide.

This parasite has recently caused numerous outbreaks in recreational water, such as
swimming pools and water parks, which are often visited by young children who are still in
diapers. The infectious form of the parasite is small and highly resistant to chlorine, so
standard filtering and chlorination may not be effective.

The authors of this article tested water that had fecal matter added to simulate a common
"fecal accident" in a swimming pool. Results showed that levels of chlorine known to
kill the parasite were no longer adequate if there was fecal matter contaminating the water,
indicating that the human waste protected the parasite from chlorine inactivation.

To prevent outbreaks of diarrhea caused by this parasite, the authors suggest changes in
pool engineering, such as improved filtering and more frequent turnover of the water pumped
into the pool. They also suggest changes in pools' policies and urge that staff of and
visitors to public pools and water parks be educated about ways to prevent waterborne disease
transmission, such as 1) staying out of the pool while ill with diarrhea, 2) not swallowing
pool water, 3) using safe diaper changing and handwashing practices, 4) giving young children
frequent bathroom breaks, and 5) encouraging swimmers to shower before entering a pool.

For more information, contact Dr. James Trout at 301-504-8496. Access the full article at http://www.cdc.gov/ncidod/EID/vol5no4/carpenter.htm.
All material in Emerging Infectious Diseases is in the public domain and may be used
without special permission; proper citation, however, is appreciated.